Below you will find information regarding the professional input the LFOA received prior to making the decision to remove the London Plane Sycamores. The Black Pines were removed due to Pine Beetle infestation. The west side of Francisco was landscaped with Sycamores but of the Blood Good sub specie are fine and will not be removed.
The additional elements that lead to the removal of the Sycamores and replacement with more appropriate species included the following;
The Board spent about $4000 this year on walkway slab replacement and grinding caused by root intrusion. Lessor contracts were let in previous years.
The Sycamores were initially planted in soil areas too small to accommodate them at full maturity
No root barriers were used which would contain the horizontal growth of the tree. Barriers have been installed with all new trees with soil areas less than 8 feet wide.
The new varieties being planted are those most appropriate for boulevard applications and provide excellent Fall color
Spreading the planting over multiple years would substantially add to the cost and the trees would be of varying size from this point on
The cost to treat the Anthracnose and Powdery Mildew would have been approximately $12-13k per year. Should unexpected rain occur after the spraying the trees would need to be treated again.
The fungicide needed could potentially drift on to pedestrians and adjacent homes
The removal was a difficult decision but determioned to be best for the corridor over time
Thanks for your understanding
As indicated in the UC notes, fungicides can offer a measure of control if they are used with very accurate timing. As the fungicides last for 7-10 days, multiple applications are required to protect the trees when they are most vulnerable. It can be very frustrating to make 2-3 spring applications that are well timed and successful only to have an early summer rain that brings on an infection.
Powdery Mildew is a topical fungus that grows on the surface of plant material. A wide variety of trees and plants can experience problems with this disease. In addition to interrupting the normal physiology of plants and trees, serious infestations are also photosynthesis inhibitors as the entire surface of a leaf can be covered.
Here is the corresponding UC paper:
Although this is an aggressive disease it is readily controlled by fungicides and can usually be eradicated with one or two applications.
Here are comments from the professionals that work on the corridor:
As I recall, back when the original plans for the Francisco corridor were being put together, El Dorado County planners were on an environmental kick and native plant material was being encouraged if not required on these projects. Some of the problems with that take years to develop or become apparent.
The native Sycamore, while quite picturesque in it’s native habitat, gnarled and twisted from decades of surviving drought and disease, carries those attributes with it where ever it is planted. A tree specie for avenue planting is generally selected because of its uniformity, resistance to disease and habits that make it easy to maintain. Simple economic and aesthetic decisions. Unfortunately with the native sycamore, the result is a collection of individuals each shaped by its hardships, and those hardships that affect them also result in the litter drop, bare trees when they should be in leaf, misshapen branching, gnarly growths and so forth. Each one could be beautiful as an individual lawn specimen, but in the broad avenue setting that diversity of shapes detracts from the stately effect generally desired. Botanist spent careers developing varieties to overcome those less desirable characteristics… shouldn’t we take advantage of that and reduce our work and costs by correcting previous mistakes? The trees are what they are and will not correct themselves.
- NOTE: Ron Allison, the current Landscape Architect, designed Windsor Point. Those are a variety of Sycamores that are NOT susceptible to Anthracnose or Powdery Mildew. Those trees will not be removed. Future removal of the sycamores will be more costly each year and will delay long term appeal of the corridor.
Regional Vice President
Arborwell. 888.969.8733 Office/Emergency 916.869.7078 Mobile
3207 Fitzgerald Rd Rancho Cordova, CA 95742 www.arborwell.com
The London Plane is susceptible to several foliage diseases which can make it aesthetically unpleasing much of the year. The primary foliar problems are Anthracnose and Powdery Mildew. While the trees can be viable and survive in the landscape there are better options available. The London Plane on Francisco are relatively young and can be replaced at a relatively low cost with, ultimately, a more valuable species.
Capital Landscape, Paul Miller:
From a maintenance perspective the London Plane trees we have on the East side of the corridor are of the variety that get Anthracnose and Powdery Mildew almost every year and this causes them to loose leaves during the summer months. Therefore they tend to look unhealthy during that time and are also very messy while dropping leaves during the summer and when we need the shade they are not much help while in that condition. Also the root system of these trees is causing damage to the sidewalk and irrigation system in several locations as we have identified.
This type of sycamore that is more susceptible powdery mildew and anthracnose can be differentiated from the Blood Good Sycamores that are resistant to powdery mildew and anthracnose by the current branch structure. The branch structure should look similar to what is shown in the picture below or at least more uniform but what we see on the East side is a very irregular canopy growth with a kind of twisted and un balanced look.
[UC – IPM site]. Sycamore, London plane tree—Platanus spp. Family Platanaceae (Plane tree family)
Sycamore is a fast-growing deciduous tree reaching 30 to 40 feet tall. It has large lobed maple-like leaves. Seed pods in the form of fuzzy ball-like clusters hang from the branches in winter. Trees can be pollarded to develop a lower canopy.
Optimum conditions for growth:
These trees are adapted to a wide range of climate zones. They tolerate most soils and do best in full sun with some deep watering in the summer. Most varieties can be affected by anthracnose and powdery mildew. If trees are regularly pollarded, choose the cultivar ‘Yarwood’ as it is highly resistant to powdery mildew and its susceptibility to anthracnose will be controlled by pruning.
California sycamore, Platanus racemosa: Sycamore anthracnose lesions typically develop along major leaf veins. If leaves are very young when infected, they can become curled and distorted with only a portion of each leaf dying.
Generally, mature leaves are resistant to infection, but when conditions are favorable, spotty lesions can occur. Heavily infected leaves fall prematurely throughout the growing season, and sometimes trees become completely defoliated. New leaf growth usually occurs after an early drop.
Anthracnose also can attack and kill twigs and branches. On some trees, cankers—sunken, infected areas with swollen edges—develop on twigs, branches, and the trunk, occasionally resulting in girdling (the destruction of the nutrient and water conducting tissues all the way around a branch or twig) and dieback. Regrowth from lateral buds can give branches a gnarled or crooked appearance